The invention relates to the field of aircraft electrical energy supply systems and more particularly to supplemental energy supplied to maintain consistent energy levels on an aircraft bus.
A DC bus line is typically maintained on an aircraft to supply energy to the electrical systems of the aircraft. An energy supplementary apparatus is connected to the DC bus line to keep the electrical systems operational during aircraft DC bus line transients or during peak short duration energy supply demand requirements by the load. The energy supplementary apparatus typically includes a two stage controlled charge and isolated boost utilizing closed loop regulators. The energy supplementary apparatus may be used in conjunction with aircraft battery supply.
Batteries are widely used to store electrical energy and may be used in energy supplementary apparatus. Batteries adequate to the high-power demands of aircraft electrical systems tend to be heavy and weight is usually a serious factor in aircraft design. Alternate energy storage elements such as super capacitors and electromechanical fly wheels may be used to provide energy for energy supplementary apparatus.
The large capacitance of super capacitors enables the storage of large amounts of energy that can be accessed at high currents. The charge deposit in a super capacitor or any capacitor, unlike most battery types, requires precise control of the capacitor's terminal voltage. The energy stored in a capacitor, being the square-low function of terminal voltage across the capacitor, dictates the use of power processing circuit that maintains a constant output voltage even during time varying voltage across the capacitor.
As can be seen, there is a need for an energy supplementary apparatus capable of providing sufficient energy levels while minimizing the battery capacity, size and weight requirement on a typical aircraft DC-bus distribution system